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The air brake system is fail safe against accidental disconnection. You can intentionally get around it if needed. Obviously they did something like that here,
by fredoralive 5y ago
The air brake system is fail safe against accidental disconnection. You can intentionally get around it if needed. Obviously they did something like that here, expecting it to be a safe setup for low speed shunting in a yard...
- flyinghamster 5y agoAlso, fail-safe only works so far. A parked car needs to have handbrakes set or wheels chocked, since the air can eventually bleed out of the reservoir and release the brakes. The Lac-Mégantic disaster [0] involved insufficient handbrakes set on a train parked on a grade. [0] https://en.wikipedia.org/wiki/Lac-M%C3%A9gantic_rail_disaster https://en.wikipedia.org/wiki/Lac-M%C3%A9gantic_rail_disaste...
- msisk6 5y agoAll US rail freight cars have a "bleed rod" that releases all the air in the brake system so you can move cars for switching. Most large railroad yards nowadays are "hump yards" where a locomotive pushes cars over a small hill and they roll down the though a series of switches with a computer monitoring their progress and activating rail mounted brakes that squeeze the sides of the wheels so they roll into other cars at a controlled speed to make up trains. Smaller yards, like in this story of the runaway, are "flat switched" where a locomotive and man power manually do all this work to put a train together. Back before railroads started reducing train crews the engineer wouldn't need to get out to align switches; they had a "switchman" who would get out and align the switches as needed.
- jvolkman 5y agoAnd if you ever see "DO NOT HUMP" on the side of a car, this is what it refers to. Crews also "kick" cars in flat yards which looks a bit more like humping in that brakeless cars roll down tracks on their own: https://youtu.be/zEWE3df6Q2s?t=248 https://youtu.be/zEWE3df6Q2s?t=248
- joncrane 5y agoThat is an amazing video. Thank you.